Abrasive article and method of making the same

ABSTRACT

An abrasive article comprises abrasive particles adhered to a substrate by a binder material. The binder material comprises an at least partially cured resole phenolic resin and an organic polymeric rheology modifier. The amount of the at least partially cured resole phenolic resin comprises from 75 to 99.99 weight percent of the combined weight of the at least partially cured resole phenolic resin and the organic polymeric rheology modifier. Methods of making the abrasive article are also disclosed.

TECHNICAL FIELD

The present disclosure relates to abrasive articles including a phenolicbinder material and abrasive particles, and methods of making the same.

BACKGROUND

Abrasive articles generally comprise abrasive particles (also known as“grains”) retained within a binder. During manufacture of various typesof abrasive articles, the abrasive particles are deposited on a bindermaterial precursor in an oriented manner (e.g., by electrostatic coatingor by some mechanical placement technique). Typically, the mostdesirable orientation of the abrasive particles is substantiallyperpendicular to the surface of the backing.

In the case of nonwoven abrasive articles, the binder material precursoris coated on a lofty open nonwoven fiber web, the abrasive particles areadhered to the binder material precursor, and then the binder materialprecursor is cured sufficiently to retain the abrasive particles duringuse.

In the case of certain coated abrasive articles (e.g., grinding discs),the backing is a relatively dense planar substrate (e.g., vulcanizedfiber or a woven or knit fabric, optionally treated with a saturant toincrease durability). A make layer precursor (or make coat) containing afirst binder material precursor is applied to the backing, and then theabrasive particles are partially embedded into the make layer precursor.Frequently, the abrasive particles are embedded in the make layerprecursor with a degree of orientation; e.g., by electrostatic coatingor by a mechanical placement technique. The make layer precursor is thenat least partially cured in order to retain the abrasive particles whena size layer precursor (or size coat) containing a second bindermaterial precursor is overlaid on the at least partially cured makelayer precursor and abrasive particles. Next, the size layer precursor,and the make layer precursor if not sufficiently cured, are cured toform the coated abrasive article.

For both of the above types of abrasive articles, it is generallydesirable that the abrasive particles remain in their originalorientation as embedded in the binder material precursor until it hasbeen sufficiently cured to fix them in place. This is especiallytroublesome when the binder precursor material is too fluid so that theparticles tip over by gravity, or if the binder precursor material istoo hard such that the particles do not adhere to the binder precursormaterial and again tip over due to gravity.

Abrasive particle tipping after deposition is especially problematicwith resole phenolic resin binder material precursors. It would bedesirable to have resole-phenolic-resin-based binder material precursorsthat the original orientation of the applied abrasive particles ismaintained until sufficient curing has occurred.

SUMMARY

The present disclosure overcomes this problem by using a resolephenolic-based curable composition (typically thixotropic) suitable foruse in manufacture of an abrasive article. The curable compositioncomprises a liquid phenolic resin and an organic polymeric rheologymodifier comprising an alkali-swellable/soluble polymer. These organicpolymeric rheology modifiers are presently discovered to provide bettercontrol of abrasive tip density across all mineral coating technologieswhich can yield abrasives with equal or better performance at lowerprecision shaped grain loadings than existing commercial products.

Organic polymeric rheology modifiers are known to give pseudoplasticflow characteristics. Particularly, Alkali-Swellable/soluble Emulsion(ASE) polymers, Hydrophobically-modified Alkali-Swellable/solubleEmulsion (HASE) polymers, and Hydrophobically-modified EthoxylatedURethane (HEUR) polymers have been used in aqueous compositions forlatex paints, personal care products, and drilling muds. In a firstaspect, the present disclosure provides a method of making an abrasivearticle comprising:

disposing a curable composition on a substrate, wherein the curablecomposition comprises a resole phenolic resin and an organic polymericrheology modifier, wherein the organic polymeric rheology modifiercomprises an alkali-swellable/soluble polymer, and wherein the amount ofresole phenolic resin comprises from 75 to 99.99 weight percent of thecombined weight of the resole phenolic resin and the organic polymericrheology modifier;

adhering abrasive particles to the curable composition; and

at least partially curing the curable composition.

In a second aspect, the present disclosure provides an abrasive articlecomprising abrasive particles adhered to a substrate by a bindermaterial comprising an at least partially cured resole phenolic resinand an organic polymeric rheology modifier, wherein the amount of resolephenolic resin comprises from 75 to 99.99 weight percent of the combinedweight of the resole phenolic resin and the organic polymeric rheologymodifier.

As used herein:

“alkali-swellable” means at least partially swellable in an aqueoussolution of a water-soluble base having a pH of greater than 7;

“alkali-swellable/soluble” means at least one of alkali-swellable oralkali-soluble (i.e., alkali-swellable and/or alkali-soluble); and

“polymer” refers to an organic polymer unless otherwise clearlyindicated.

Features and advantages of the present disclosure will be furtherunderstood upon consideration of the detailed description as well as theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional side view of an exemplary coated abrasivearticle 100 according to the present disclosure.

FIG. 2A is a perspective view of exemplary nonwoven abrasive article 200according to the present disclosure.

FIG. 2B is an enlarged view of region 2B of nonwoven abrasive article200 shown in FIG. 2A.

Repeated use of reference characters in the specification and drawingsis intended to represent the same or analogous features or elements ofthe disclosure. It should be understood that numerous othermodifications and embodiments can be devised by those skilled in theart, which fall within the scope and spirit of the principles of thedisclosure. The figures may not be drawn to scale.

DETAILED DESCRIPTION

An exemplary embodiment of a coated abrasive article according to thepresent disclosure is depicted in FIG. 1. Referring now to FIG. 1,coated abrasive article 100 has backing 120 and abrasive layer 130.Abrasive layer 130 includes abrasive particles 140 secured to majorsurface 170 of backing 120 (substrate) by make layer 150 and size layer160.

Coated abrasive articles according to the present disclosure may includeadditional layers such as, for example, an optional supersize layer thatis superimposed on the abrasive layer, or a backing antistatic treatmentlayer may also be included, if desired.

Useful backings include, for example, those known in the art for makingcoated abrasive articles. Typically, the backing has two opposed majorsurfaces, although this is not a requirement. The thickness of thebacking generally ranges from about 0.02 to about 5 millimeters,desirably from about 0.05 to about 2.5 millimeters, and more desirablyfrom about 0.1 to about 1.0 millimeter, although thicknesses outside ofthese ranges may also be useful. Generally, the strength of the backingshould be sufficient to resist tearing or other damage during abradingprocesses. The thickness and smoothness of the backing should also besuitable to provide the desired thickness and smoothness of the coatedabrasive article; for example, depending on the intended application oruse of the coated abrasive article.

Exemplary backings include: dense nonwoven fabrics (e.g., needletacked,meltspun, spunbonded, hydroentangled, or meltblown nonwoven fabrics),knitted fabrics, stitchbonded and/or woven fabrics; scrims; polymerfilms; treated versions thereof; and combinations of two or more ofthese materials.

Fabric backings can be made from any known fibers, whether natural,synthetic or a blend of natural and synthetic fibers. Examples of usefulfiber materials include fibers or yarns comprising polyester (forexample, polyethylene terephthalate), polyamide (for example,hexamethylene adipamide, polycaprolactam), polypropylene, acrylic(formed from a polymer of acrylonitrile), cellulose acetate,polyvinylidene chloride-vinyl chloride copolymers, vinylchloride-acrylonitrile copolymers, graphite, polyimide, silk, cotton,linen, jute, hemp, or rayon. Useful fibers may be of virgin materials orof recycled or waste materials reclaimed from garment cuttings, carpetmanufacturing, fiber manufacturing, or textile processing, for example.Useful fibers may be homogenous or a composite such as a bicomponentfiber (for example, a co-spun sheath-core fiber). The fibers may betensilized and crimped, but may also be continuous filaments such asthose formed by an extrusion process.

The backing may have any suitable basis weight; typically, in a range offrom 100 to 1250 grams per square meter (gsm), more typically 450 to 600gsm, and even more typically 450 to 575 gsm. In many embodiments (e.g.,abrasive belts and sheets), the backing typically has good flexibility;however, this is not a requirement (e.g., vulcanized fiber discs). Topromote adhesion of binder resins to the backing, one or more surfacesof the backing may be modified by known methods including coronadischarge, ultraviolet light exposure, electron beam exposure, flamedischarge, and/or scuffing.

The make layer is formed by at least partially curing a make layerprecursor that is a curable composition according to the presentdisclosure. The curable composition comprises a resole phenolic resinand an organic polymeric rheology modifier that aids in preserving theinitial placement and orientation of the abrasive particles duringmanufacture.

Phenolic resins are generally formed by condensation of phenol andformaldehyde, and are usually categorized as resole or novolac phenolicresins. Novolac phenolic resins are acid-catalyzed and have a molarratio of formaldehyde to phenol of less than 1:1. Resole (also resol)phenolic resins can be catalyzed by alkaline catalysts, and the molarratio of formaldehyde to phenol is greater than or equal to one,typically between 1.0 and 3.0, thus presenting pendant methylol groups.Alkaline catalysts suitable for catalyzing the reaction between aldehydeand phenolic components of resole phenolic resins include sodiumhydroxide, barium hydroxide, potassium hydroxide, calcium hydroxide,organic amines, and sodium carbonate, all as solutions of the catalystdissolved in water.

Resole phenolic resins are typically coated as a solution with waterand/or organic solvent (e.g., alcohol). Typically, the solution includesabout 70 percent to about 85 percent solids by weight, although otherconcentrations may be used. If the solids content is very low, then moreenergy is required to remove the water and/or solvent. If the solidscontent is very high, then the viscosity of the resulting phenolic resinis too high which typically leads to processing problems.

Phenolic resins are well-known and readily available from commercialsources. Examples of commercially available resole phenolic resinsuseful in practice of the present disclosure include those marketed byDurez Corporation under the trade designation VARCUM (e.g., 29217,29306, 29318, 29338, 29353); those marketed by Ashland Chemical Co. ofBartow, Fla. under the trade designation AEROFENE (e.g., AEROFENE 295);and those marketed by Kangnam Chemical Company Ltd. of Seoul, SouthKorea under the trade designation PHENOLITE (e.g., PHENOLITE TD-2207).

A general discussion of phenolic resins and their manufacture is givenin Kirk-Othmer, Encyclopedia of Chemical Technology, 4th Ed., John Wiley& Sons, 1996, New York, Vol. 18, pp. 603-644.

In addition to the resole phenolic resin, the curable compositioncontains an organic polymeric rheology modifier that comprises analkali-swellable/soluble polymer. The curable composition comprises aresole phenolic resin (typically diluted with water) and an organicpolymeric rheology modifier that comprises an alkali-swellable/solublepolymer. On a solids basis, wherein the amount of the resole phenolicresin comprises from 75 to 99.99 weight percent (preferably 82 to 99.99weight percent, and even more preferably 88 to 99.99 weight percent) ofthe combined weight of the resole phenolic resin and the organicpolymeric rheology modifier. Accordingly, the curable compositioncontains from 1 to 25 weight percent, preferably 1 to 18 weight percent,and more preferably 1 to 12 weight percent of the organic polymericrheology modifier, based on the combined weight of the resole phenolicresin and the organic polymeric rheology modifier. Combinations of morethan one resole phenolic resin and/or more than one organic polymericrheology modifier may be used if desired.

Alkali-swellable/soluble polymers suitable for use as the organicpolymeric rheology modifier include, for example,Alkali-Swellable/soluble Emulsion (ASE) organic polymers,Hydrophobically-modified Alkali-Swellable/soluble Emulsion polymers(HASE), and Hydrophobically modified Ethoxylated URethane polymers(HEUR).

The organic polymeric rheology modifier may be chosen fromalkali-swellable/soluble acrylic emulsion polymers (ASE),Hydrophobically-modified alkali-swellable/soluble acrylic emulsionpolymers (HASE), and Hydrophobically-modified Ethoxylated URethane(HEUR) organic polymers.

Alkali-Swellable/soluble Emulsion (ASE) rheology modifiers aredispersions of insoluble acrylic polymers in water have a highpercentage of acid groups distributed throughout their polymer chains.When these acid groups are neutralized, the salt that is formed ishydrated. Depending on the concentration of acid groups, the molecularweight and degree of crosslinking, the salt either swells in aqueoussolutions or becomes completely water-soluble.

As the concentration of neutralized polymer in an aqueous formulationincreases, the polymer chains swell, thereby causing the viscosity toincrease.

ASE polymers can be synthesized from acid and acrylate co-monomers, andare generally made through emulsion polymerization. Exemplarycommercially available ASE polymers include ACUSOL 810A, ACUSOL 830,ACUSOL 835, and ACUSOL 842 polymers.

Hydrophobically-modified Alkali-Swellable/soluble Emulsion (HASE)polymers are commonly employed to modify the rheological properties ofaqueous emulsion systems. Under the influence of a base, organic orinorganic, the HASE particles gradually swell and expand to form athree-dimensional network by intermolecular hydrophobic aggregationbetween HASE polymer chains and/or with components of the emulsion. Thisnetwork, combined with the hydrodynamic exclusion volume created by theexpanded HASE chains, produces the desired thickening effect. Thisnetwork is sensitive to applied stress, breaks down wider shear andrecovers when the stress is relieved.

HASE rheology modifiers can be prepared from the following monomers: (a)an ethylenically unsaturated carboxylic acid, (b) a nonionicethylenically unsaturated monomer, and (c) an ethylenically unsaturatedhydrophobic monomer. Representative HASE polymer systems include thoseshown in EP 226097 B1 (van Phung et al.), EP 705852 B1 (Doolan et al.).U.S. Pat. No. 4,384,096 (Sonnabend) and U.S. Pat. No. 5,874,495(Robinson).

Exemplary commercially available HASE polymers include those marketed byDow Chemical under the trade designations ACUSOL 801S, ACUSOL 805S,ACUSOL 820, and ACUSOL 823.

ASE and HASE rheology modifiers are pH-triggered thickeners. Whether theemulsion polymer in each is water-swellable or water-soluble typicallydepends on its molecular weight. Both forms are acceptable. Furtherdetails concerning synthesis of ASE and HASE polymers can be found, forexample, in U.S. Pat. No. 9,631,165 (Droege et al.).

Hydrophobically-modified Ethoxylated URethane (HEUR) polymers aregenerally synthesized from an alcohol, a diisocyanate and one or morepolyalkylene glycols. HEURs are water-soluble polymers containinghydrophobic groups, and are classified as associative thickeners becausethe hydrophobic groups associate with one another in water. UnlikeHASEs, HEURs are nonionic substances and are not dependent on alkali foractivation of the thickening mechanism. They develop intra- orintermolecular links as their hydrophobic groups associate with otherhydrophobic ingredients in a given formulation. As a general rule, thestrength of the association depends on the number, size, and frequencyof the hydrophobic capping or blocking units. HEURs develop micelles aswould a normal surfactant. The micelles then link between the otheringredients by associating with their surfaces. This builds athree-dimensional network.

Exemplary commercially available HEUR polymers include those marketed byDow Chemical under the trade designations ACUSOL 880, ACUSOL 882,ACRYSOL RM-2020, and ACRYSOL RM-8W.

Further details concerning HEURs can be found, for example, in U.S. Pat.Appl. Publ. No. 2017/0198238 (Kensicher et al.) and 2017/0130072(McCulloch et al.) and U.S. Pat. No. 7,741,402 (Bobsein et al.) and U.S.Pat. No. 8,779,055 (Rabasco et al.).

Make layers and size layers are formed by at least partially curingcorresponding precursors (i.e., a make layer precursor and a size layerprecursor).

The make layer precursor comprises a curable composition according tothe present disclosure. The curable composition may also containadditives such as fibers, lubricants, wetting agents, surfactants,pigments, dyes, antistatic agents (e.g., carbon black, vanadium oxide,and/or graphite), coupling agents (e.g., silanes, titanates, and/orzircoaluminates), plasticizers, suspending agents, and the like. Theamounts of these optional additives are selected to provide thepreferred properties. The coupling agents can improve adhesion to theabrasive particles and/or filler. The curable composition may bethermally-cured, radiation-cured, or a combination thereof.

The curable composition may also contain filler materials, diluentabrasive particles (e.g., as described hereinbelow), or grinding aids,typically in the form of a particulate material. Typically, theparticulate materials are inorganic materials. Examples of usefulfillers for this disclosure include: metal carbonates (e.g., calciumcarbonate (e.g., chalk, calcite, marl, travertine, marble andlimestone), calcium magnesium carbonate, sodium carbonate, magnesiumcarbonate), silica (e.g., quartz, glass beads, glass bubbles and glassfibers) silicates (e.g., talc, clays, (montmorillonite) feldspar, mica,calcium silicate, calcium metasilicate, sodium aluminosilicate, sodiumsilicate) metal sulfates (e.g., calcium sulfate, barium sulfate, sodiumsulfate, aluminum sodium sulfate, aluminum sulfate), gypsum,vermiculite, wood flour, aluminum trihydrate, carbon black, metal oxides(e.g., calcium oxide (lime), aluminum oxide, titanium dioxide), andmetal sulfites (e.g., calcium sulfite).

The size layer precursor comprises a thermosetting resin. Examples ofsuitable thermosetting resins that may be useful for the size layerprecursor include, for example, free-radically polymerizable monomersand/or oligomers, epoxy resins, acrylic resins, urethane resins,phenolic resins, urea-formaldehyde resins, melamine-formaldehyde resins,aminoplast resins, cyanate resins, or combinations thereof. Usefulbinder precursors include thermally curable resins and radiation curableresins, which may be cured, for example, thermally and/or by exposure toradiation. Additional details concerning size layer precursors may befound in U.S. Pat. No. 4,588,419 (Caul et al.), U.S. Pat. No. 4,751,138(Tumey et al.), and U.S. Pat. No. 5,436,063 (Follett et al.).

The size layer precursor may also be modified by various additives(e.g., fibers, lubricants, wetting agents, surfactants, pigments, dyes,antistatic agents (e.g., carbon black, vanadium oxide, and/orgraphite.), coupling agents (e.g., silanes, titanates, zircoaluminates,etc.), plasticizers, suspending agents). Catalysts and/or initiators maybe added to thermosetting resins; for example, according to conventionalpractice and depending on the resin used.

Heat energy is commonly applied to advance curing of the thermosettingresins (e.g., curable compositions according to the present disclosure);however, other sources of energy (e.g., microwave radiation, infraredlight, ultraviolet light, visible light, may also be used). Theselection will generally be dictated by the particular resin systemselected.

Useful abrasive particles may be the result of a crushing operation(e.g., crushed abrasive particles that have been sorted for shape andsize) or the result of a shaping operation (i.e., shaped abrasiveparticles) in which an abrasive precursor material is shaped (e.g.,molded), dried, and converted to ceramic material. Combinations ofabrasive particles resulting from crushing with abrasive particlesresulting from a shaping operation may also be used. The abrasiveparticles may be in the form of, for example, individual particles,agglomerates, composite particles, and mixtures thereof.

The abrasive particles should have sufficient hardness and surfaceroughness to function as crushed abrasive particles in abradingprocesses. Preferably, the abrasive particles have a Mohs hardness of atleast 4, at least 5, at least 6, at least 7, or even at least 8.

Suitable abrasive particles include, for example, crushed abrasiveparticles comprising fused aluminum oxide, heat-treated aluminum oxide,white fused aluminum oxide, ceramic aluminum oxide materials such asthose commercially available as 3M CERAMIC ABRASIVE GRAIN from 3MCompany, St. Paul, Minn., brown aluminum oxide, blue aluminum oxide,silicon carbide (including green silicon carbide), titanium diboride,boron carbide, tungsten carbide, garnet, titanium carbide, diamond,cubic boron nitride, garnet, fused alumina zirconia, iron oxide,chromia, zirconia, titania, tin oxide, quartz, feldspar, flint, emery,sol-gel-derived ceramic (e.g., alpha alumina), and combinations thereof.Examples of sol-gel-derived abrasive particles from which the abrasiveparticles can be isolated, and methods for their preparation can befound, in U.S. Pat. No. 4,314,827 (Leitheiser et al.); U.S. Pat. No.4,623,364 (Cottringer et al.); U.S. Pat. No. 4,744,802 (Schwabel), U.S.Pat. No. 4,770,671 (Monroe et al.); and U.S. Pat. No. 4,881,951 (Monroeet al.). It is also contemplated that the abrasive particles couldcomprise abrasive agglomerates such, for example, as those described inU.S. Pat. No. 4,652,275 (Bloecher et al.) or U.S. Pat. No. 4,799,939(Bloecher et al.). In some embodiments, the abrasive particles may besurface-treated with a coupling agent (e.g., an organosilane couplingagent) or other physical treatment (e.g., iron oxide or titanium oxide)to enhance adhesion of the crushed abrasive particles to the binder. Theabrasive particles may be treated before combining them with the binder,or they may be surface treated in situ by including a coupling agent tothe binder.

Preferably, the abrasive particles (and especially the abrasiveparticles) comprise ceramic abrasive particles such as, for example,sol-gel-derived polycrystalline alpha alumina particles. Ceramicabrasive particles composed of crystallites of alpha alumina, magnesiumalumina spinel, and a rare earth hexagonal aluminate may be preparedusing sol-gel precursor alpha alumina particles according to methodsdescribed in, for example, U.S. Pat. No. 5,213,591 (Celikkaya et al.)and U.S. Publ. Pat. Appln. Nos. 2009/0165394 A1 (Culler et al.) and2009/0169816 A1 (Erickson et al.). Further details concerning methods ofmaking sol-gel-derived abrasive particles can be found in, for example,U.S. Pat. No. 4,314,827 (Leitheiser); U.S. Pat. No. 5,152,917 (Pieper etal.); U.S. Pat. No. 5,435,816 (Spurgeon et al.); U.S. Pat. No. 5,672,097(Hoopman et al.); U.S. Pat. No. 5,946,991 (Hoopman et al.); U.S. Pat.No. 5,975,987 (Hoopman et al.); and U.S. Pat. No. 6,129,540 (Hoopman etal.); and in U.S. Publ. Pat. Appln. No. 2009/0165394 A1 (Culler et al.).

In some preferred embodiments, useful abrasive particles (especially inthe case of the abrasive particles) may be shaped abrasive particles canbe found in U.S. Pat. No. 5,201,916 (Berg); U.S. Pat. No. 5,366,523(Rowenhorst (Re 35,570)); and U.S. Pat. No. 5,984,988 (Berg). U.S. Pat.No. 8,034,137 (Erickson et al.) describes alumina abrasive particlesthat have been formed in a specific shape, then crushed to form shardsthat retain a portion of their original shape features. In someembodiments, the abrasive particles are precisely-shaped (i.e., theparticles have shapes that are at least partially determined by theshapes of cavities in a production tool used to make them. Detailsconcerning such abrasive particles and methods for their preparation canbe found, for example, in U.S. Pat. No. 8,142,531 (Adefris et al.); U.S.Pat. No. 8,142,891 (Culler et al.); and U.S. Pat. No. 8,142,532(Erickson et al.); and in U.S. Pat. Appl. Publ. Nos. 2012/0227333(Adefris et al.); 2013/0040537 (Schwabel et al.); and 2013/0125477(Adefris). One particularly useful precisely-shaped abrasive particleshape is that of a truncated triangular pyramid with sloping sidewalls;for example as set forth in the above cited references.

Surface coatings on the abrasive particles may be used to improve theadhesion between the abrasive particles and a binder material, or to aidin electrostatic deposition of the abrasive particles. In oneembodiment, surface coatings as described in U.S. Pat. No. 5,352,254(Celikkaya) in an amount of 0.1 to 2 percent surface coating to abrasiveparticle weight may be used. Such surface coatings are described in U.S.Pat. No. 5,213,591 (Celikkaya et al.); U.S. Pat. No. 5,011,508 (Wald etal.); U.S. Pat. No. 1,910,444 (Nicholson); U.S. Pat. No. 3,041,156(Rowse et al.); U.S. Pat. No. 5,009,675 (Kunz et al.); U.S. Pat. No.5,085,671 (Martin et al.); U.S. Pat. No. 4,997,461 (Markhoff-Matheny etal.); and U.S. Pat. No. 5,042,991 (Kunz et al.). Additionally, thesurface coating may prevent shaped abrasive particles from capping.Capping is the term to describe the phenomenon where metal particlesfrom the workpiece being abraded become welded to the tops of theabrasive particles. Surface coatings to perform the above functions areknown to those of skill in the art.

In some embodiments, the abrasive particles may be selected to have alength and/or width in a range of from 0.1 micrometers to 3.5millimeters (mm), more typically 0.05 mm to 3.0 mm, and more typically0.1 mm to 2.6 mm, although other lengths and widths may also be used.

The abrasive particles may be selected to have a thickness in a range offrom 0.1 micrometer to 1.6 mm, more typically from 1 micrometer to 1.2mm, although other thicknesses may be used. In some embodiments,abrasive particles may have an aspect ratio (length to thickness) of atleast 2, 3, 4, 5, 6, or more.

Typically, crushed abrasive particles are independently sized accordingto an abrasives industry recognized specified nominal grade. Exemplaryabrasive industry recognized grading standards include those promulgatedby ANSI (American National Standards Institute), FEPA (Federation ofEuropean Producers of Abrasives), and JIS (Japanese IndustrialStandard). Such industry accepted grading standards include, forexample: ANSI 4, ANSI 6, ANSI 8, ANSI 16, ANSI 24, ANSI 30, ANSI 36,ANSI 40, ANSI 50, ANSI 60, ANSI 80, ANSI 100, ANSI 120, ANSI 150, ANSI180, ANSI 220, ANSI 240, ANSI 280, ANSI 320, ANSI 360, ANSI 400, andANSI 600; FEPA P8, FEPA P12, FEPA P16, FEPA P24, FEPA P30, FEPA P36,FEPA P40, FEPA P50, FEPA P60, FEPA P80, FEPA P100, FEPA P120, FEPA P150,FEPA P180, FEPA P220, FEPA P320, FEPA P400, FEPA P500, FEPA P600, FEPAP800, FEPA P1000, FEPA P1200; FEPA F8, FEPA F12, FEPA F16, and FEPA F24;and JIS 8, JIS 12, JIS 16, JIS 24, JIS 36, JIS 46, JIS 54, JIS 60, JIS80, JIS 100, JIS 150, JIS 180, JIS 220, JIS 240, JIS 280, JIS 320, JIS360, JIS 400, JIS 400, JIS 600, JIS 800, JIS 1000, JIS 1500, JIS 2500,JIS 4000, JIS 6000, JIS 8000, and JIS 10,000. More typically, thecrushed aluminum oxide particles and the non-seeded sol-gel derivedalumina-based abrasive particles are independently sized to ANSI 60 and80, or FEPA F36, F46, F54 and F60 or FEPA P60 and P80 grading standards.

Alternatively, the abrasive particles can be graded to a nominalscreened grade using U.S.A. Standard Test Sieves conforming to ASTM E-11“Standard Specification for Wire Cloth and Sieves for Testing Purposes”.ASTM E-11 prescribes the requirements for the design and construction oftesting sieves using a medium of woven wire cloth mounted in a frame forthe classification of materials according to a designated particle size.A typical designation may be represented as −18+20 meaning that theshaped abrasive particles pass through a test sieve meeting ASTM E-11specifications for the number 18 sieve and are retained on a test sievemeeting ASTM E-11 specifications for the number 20 sieve. In oneembodiment, the shaped abrasive particles have a particle size such thatmost of the particles pass through an 18 mesh test sieve and can beretained on a 20, 25, 30, 35, 40, 45, or 50 mesh test sieve. In variousembodiments, the shaped abrasive particles can have a nominal screenedgrade comprising: −18+20, −20+25, −25+30, −30+35, −35+40, −40+45,−45+50, −50+60, −60+70, −70+80, −80+100, −100+120, −120+140, −140+170,−170+200, −200+230, −230+270, −270+325, −325+400, −400+450, −450+500, or−500+635. Alternatively, a custom mesh size could be used such as−90+100.

A grinding aid is a material that has a significant effect on thechemical and physical processes of abrading, which results in improvedperformance. Grinding aids encompass a wide variety of differentmaterials and can be inorganic or organic based. Examples of chemicalgroups of grinding aids include waxes, organic halide compounds, halidesalts and metals and their alloys. The organic halide compounds willtypically break down during abrading and release a halogen acid or agaseous halide compound. Examples of such materials include chlorinatedwaxes like tetrachloronaphthalene, pentachloronaphthalene, and polyvinylchloride. Examples of halide salts include sodium chloride, potassiumcryolite, sodium cryolite, ammonium cryolite, potassiumtetrafluoroborate, sodium tetrafluoroborate, silicon fluorides,potassium chloride, and magnesium chloride. Examples of metals include,tin, lead, bismuth, cobalt, antimony, cadmium, iron, and titanium.

Other miscellaneous grinding aids include sulfur, organic sulfurcompounds, graphite, and metallic sulfides. A combination of differentgrinding aids may be used, and in some instances this may produce asynergistic effect.

Grinding aids can be particularly useful in coated abrasives. In coatedabrasive articles, grinding aid is typically used in a supersize coat,which is applied over the surface of the abrasive particles. Sometimes,however, the grinding aid is added to the size coat. Typically, theamount of grinding aid incorporated into coated abrasive articles areabout 50-800 grams per square meter (g/m²), preferably about 80-475g/m².

Further details regarding coated abrasive articles and methods of theirmanufacture can be found, for example, in U.S. Pat. No. 4,734,104(Broberg); U.S. Pat. No. 4,737,163 (Larkey); U.S. Pat. No. 5,203,884(Buchanan et al.); U.S. Pat. No. 5,152,917 (Pieper et al.); U.S. Pat.No. 5,378,251 (Culler et al.); U.S. Pat. No. 5,436,063 (Follett et al.);U.S. Pat. No. 5,496,386 (Broberg et al.); U.S. Pat. No. 5,609,706(Benedict et al.); U.S. Pat. No. 5,520,711 (Helmin); U.S. Pat. No.5,961,674 (Gagliardi et al.), and U.S. Pat. No. 5,975,988(Christianson).

Nonwoven abrasive articles typically include an open porous lofty fiberweb having abrasive particles distributed throughout the structure andadherently bonded therein by a resole-phenolic-resin-based bindermaterial according to the present disclosure. Examples of filamentsinclude polyester fibers, polyamide fibers, and polyaramid fibers.

An exemplary embodiment of a nonwoven abrasive article 200 is shown inFIGS. 2A and 2B. Referring now to FIGS. 2A and 2B, lofty openlow-density fibrous web 210 is formed of entangled fibers 115. Abrasiveparticles 140 are secured to fibrous web 210 on exposed surfaces offibers 115 by binder material 250, which also binds fibers 115 togetherat points where they contact one another, resulting in cutting pointsbeing outwardly oriented relative to fibers 115.

Nonwoven fiber webs suitable for use are known in the abrasives art.Typically, the nonwoven fiber web comprises an entangled web of fibers.The fibers may comprise continuous fiber, staple fiber, or a combinationthereof. For example, the fiber web may comprise staple fibers having alength of at least about 20 millimeters (mm), at least about 30 mm, orat least about 40 mm, and less than about 110 mm, less than about 85 mm,or less than about 65 mm, although shorter and longer fibers (e.g.,continuous filaments) may also be useful. The fibers may have a finenessor linear density of at least about 1.7 decitex (dtex, i.e., grams/10000meters), at least about 6 dtex, or at least about 17 dtex, and less thanabout 560 dtex, less than about 280 dtex, or less than about 120 dtex,although fibers having lesser and/or greater linear densities may alsobe useful. Mixtures of fibers with differing linear densities may beuseful, for example, to provide an abrasive article that upon use willresult in a specifically preferred surface finish. If a spunbondnonwoven is used, the filaments may be of substantially larger diameter,for example, up to 2 mm or more in diameter.

The fiber web may be made, for example, by conventional air laid,carded, stitch bonded, spun bonded, wet laid, and/or melt blownprocedures. Air laid fiber webs may be prepared using equipment such as,for example, that available under the trade designation RANDO WEBBERfrom Rando Machine Company of Macedon, N.Y.

Nonwoven fiber webs are typically selected to be compatible withadhering binders and abrasive particles while also being compatible withother components of the article, and typically can withstand processingconditions (e.g., temperatures) such as those employed duringapplication and curing of the curable binder precursor. The fibers maybe chosen to affect properties of the abrasive article such as, forexample, flexibility, elasticity, durability or longevity, abrasiveness,and finishing properties. Examples of fibers that may be suitableinclude natural fibers, synthetic fibers, and mixtures of natural and/orsynthetic fibers. Examples of synthetic fibers include those made frompolyester (e.g., polyethylene terephthalate), nylon (e.g., hexamethyleneadipamide, polycaprolactam), polypropylene, acrylonitrile (i.e.,acrylic), rayon, cellulose acetate, polyvinylidene chloride-vinylchloride copolymers, and vinyl chloride-acrylonitrile copolymers.Examples of suitable natural fibers include cotton, wool, jute, andhemp. The fiber may be of virgin material or of recycled or wastematerial, for example, reclaimed from garment cuttings, carpetmanufacturing, fiber manufacturing, or textile processing. The fiber maybe homogenous or a composite such as a bicomponent fiber (e.g., aco-spun sheath-core fiber). The fibers may be tensilized and crimped,but may also be continuous filaments such as those formed by anextrusion process. Combinations of fibers may also be used.

Prior to coating and/or impregnation with the curable composition (i.e.,a binder precursor composition), the nonwoven fiber web typically has aweight per unit area (i.e., basis weight) of at least about 50 grams persquare meter (gsm), at least about 100 gsm, or at least about 150 gsm;and/or less than about 600 gsm, less than about 500 gsm, or less thanabout 400 gsm, as measured prior to any coating (e.g., with the curablebinder precursor or optional pre-bond resin), although greater andlesser basis weights may also be used. In addition, prior toimpregnation with the curable binder precursor, the fiber web typicallyhas a thickness of at least about 3 mm, at least about 6 mm, or at leastabout 10 mm; and/or less than about 100 mm, less than about 50 mm, orless than about 25 mm, although greater and lesser thicknesses may alsobe useful.

Frequently, as known in the abrasives art, it is useful to apply aprebond resin to the nonwoven fiber web prior to coating with thecurable binder precursor. The prebond resin serves, for example, to helpmaintain the nonwoven fiber web integrity during handling, and may alsofacilitate bonding of the urethane binder to the nonwoven fiber web.Examples of prebond resins include phenolic resins, urethane resins,hide glue, acrylic resins, urea-formaldehyde resins,melamine-formaldehyde resins, epoxy resins, and combinations thereof.The amount of pre-bond resin used in this manner is typically adjustedtoward the minimum amount consistent with bonding the fibers together attheir points of crossing contact. In those cases, wherein the nonwovenfiber web includes thermally bondable fibers, thermal bonding of thenonwoven fiber web may also be helpful to maintain web integrity duringprocessing.

In those nonwoven abrasive articles including a lofty open nonwovenfiber web (e.g., hand pads, and surface conditioning discs and belts,flap brushes, or nonwoven abrasive webs used to make unitized orconvolute abrasive wheels) many interstices between adjacent fibers thatare substantially unfilled by the binder and abrasive particles,resulting in a composite structure of extremely low density having anetwork on many relatively large intercommunicated voids. The resultinglightweight, lofty, extremely open fibrous construction is essentiallynon-clogging and non-filling in nature, particularly when used inconjunction with liquids such as water and oils. These structures alsocan be readily cleaned upon simple flushing with a cleansing liquid,dried, and left for substantial periods of time, and then reused.Towards these ends, the voids in these nonwoven abrasive articles maymake up at least about 75 percent, and preferably more, of the totalspace occupied by the composite structure.

One method of making nonwoven abrasive articles according to the presentdisclosure includes the steps in the following order: applying a prebondcoating to the nonwoven fiber web (e.g., by roll-coating or spraycoating), curing the prebond coating, impregnating the nonwoven fiberweb with a make layer precursor that is a curable binder materialprecursor according to the present disclosure (e.g., by roll-coating orspray coating), applying abrasive particles to the make layer precursor,at least partially curing make layer precursor, and then optionallyapplying a size layer precursor (e.g., as described herein above), andcuring it and the make layer precursor (e.g., as described hereinabove),if necessary.

Further details regarding nonwoven abrasive articles and methods fortheir manufacture can be found, for example, in U.S. Pat. No. 2,958,593(Hoover et al.); U.S. Pat. No. 4,227,350 (Fitzer); U.S. Pat. No.4,991,362 (Heyer et al.); U.S. Pat. No. 5,712,210 (Windisch et al.);U.S. Pat. No. 5,591,239 (Edblom et al.); U.S. Pat. No. 5,681,361(Sanders); U.S. Pat. No. 5,858,140 (Berger et al.); U.S. Pat. No.5,928,070 (Lux); and U.S. Pat. No. 6,017,831 (Beardsley et al.).

In some embodiments, the substrate comprises a fiber scrim, for example,in the case of screen abrasives, or if included in bonded abrasives suchas, for example, cutoff wheels and depressed center grinding wheels.Suitable fiber scrims may include woven, and knitted cloths, forexample, which may include inorganic and/or organic fibers. For example,the fibers in the scrim may include wire, ceramic fiber, glass fiber(for example, fiberglass), and organic fibers (for example, naturaland/or synthetic organic fibers). Examples of organic fibers includecotton fibers, jute fibers, and canvas fibers. Examples of syntheticfibers include nylon fibers, rayon fibers, polyester fibers, andpolyimide fibers).

Abrasive articles according to the present disclosure are useful, forexample, for abrading a workpiece. Such a method may comprise:frictionally contacting an abrasive articles according to the presentdisclosure with a surface of the workpiece, and moving at least one ofthe abrasive article and the surface of the workpiece relative to theother to abrade at least a portion of the surface of the workpiece.Methods for abrading with abrasive articles according to the presentdisclosure include, for example, snagging (i.e., high-pressure highstock removal) to polishing (e.g., polishing medical implants withcoated abrasive belts), wherein the latter is typically done with finergrades (e.g., ANSI 220 and finer) of abrasive particles. The size of theabrasive particles used for a particular abrading application will beapparent to those skilled in the art.

Abrading may be carried out dry or wet. For wet abrading, the liquid maybe introduced supplied in the form of a light mist to complete flood.Examples of commonly used liquids include: water, water-soluble oil,organic lubricant, and emulsions. The liquid may serve to reduce theheat associated with abrading and/or act as a lubricant. The liquid maycontain minor amounts of additives such as bactericide, antifoamingagents, and the like.

Examples of workpieces include aluminum metal, carbon steels, mildsteels (e.g., 1018 mild steel and 1045 mild steel), tool steels,stainless steel, hardened steel, titanium, glass, ceramics, wood,wood-like materials (e.g., plywood and particle board), paint, paintedsurfaces, and organic coated surfaces. The applied force during abradingtypically ranges from about 1 to about 100 kilograms (kg), althoughother pressures can also be used.

SELECT EMBODIMENTS OF THE PRESENT DISCLOSURE

In a first embodiment, the present disclosure provides a method ofmaking an abrasive article comprising:

disposing a curable composition on a substrate, wherein the curablecomposition comprises a resole phenolic resin and an organic polymericrheology modifier, wherein the organic polymeric rheology modifiercomprises an alkali-swellable/soluble polymer, and wherein, on a solidsbasis, the amount of the resole phenolic resin comprises from 75 to99.99 weight percent of the combined weight of the resole phenolic resinand the organic polymeric rheology modifier;

adhering abrasive particles to the curable composition; and

at least partially curing the curable composition.

In a second embodiment, the present disclosure provides a method ofmaking an abrasive article according to the first embodiment, whereinthe organic polymeric rheology modifier is selected from the groupconsisting of alkali-swellable/soluble acrylic polymers,hydrophobically-modified alkali-swellable/soluble acrylic polymers,hydrophobically-modified ethoxylated urethane polymers, and combinationsthereof.

In a third embodiment, the present disclosure provides a method ofmaking an abrasive article according to the first or second embodiment,wherein, on a solids basis, the amount of the resole phenolic resincomprises from 85 to 99.99 weight percent of the combined weight of theresole phenolic resin and the organic polymeric rheology modifier.

In a fourth embodiment, the present disclosure provides a method ofmaking an abrasive article according to any one of the first to thirdembodiments, wherein the abrasive particles comprise shaped abrasiveparticles.

In a fifth embodiment, the present disclosure provides a method ofmaking an abrasive article according to the fourth embodiment, whereinthe shaped abrasive particles comprise precisely-shaped abrasiveparticles.

In a sixth embodiment, the present disclosure provides a method ofmaking an abrasive article according to the fourth embodiment, whereinthe shaped abrasive particles comprise precisely-shaped triangularplatelets.

In a seventh embodiment, the present disclosure provides a method ofmaking an abrasive article according to any one of the first to sixthembodiments, wherein the substrate comprises a backing member havingfirst and second opposed major surfaces, the method further comprising:

disposing a size layer precursor onto at least a portion of the abrasiveparticles and said at least partially cured curable composition; and

at least partially curing the size layer precursor to provide a coatedabrasive article.

In an eighth embodiment, the present disclosure provides a method ofmaking an abrasive article according to any one of the first to seventhembodiments, wherein the substrate comprises a lofty open nonwoven fiberweb.

In a ninth embodiment, the present disclosure provides a method ofmaking an abrasive article according to any one of the first to eighthembodiments, wherein the substrate comprises a fiber scrim.

In a tenth embodiment, the present disclosure provides an abrasivearticle comprising abrasive particles adhered to a substrate by a bindermaterial comprising an at least partially cured resole phenolic resinand an organic polymeric rheology modifier, wherein the amount of the atleast partially cured resole phenolic resin comprises from 75 to 99.99weight percent of the combined weight of the at least partially curedresole phenolic resin and the organic polymeric rheology modifier.

In an eleventh embodiment, the present disclosure provides an abrasivearticle according to the tenth embodiment, wherein the organic polymericrheology modifier is selected from the group consisting ofalkali-swellable/soluble acrylic polymers, hydrophobically-modifiedalkali-swellable/soluble acrylic polymers, hydrophobically-modifiedethoxylated urethane polymers, and combinations thereof.

In a twelfth embodiment, the present disclosure provides an abrasivearticle according to the tenth or eleventh embodiment, wherein theamount of the at least partially cured resole phenolic resin comprisesfrom 85 to 99.99 weight percent of the combined weight of the at leastpartially cured resole phenolic resin and the organic polymeric rheologymodifier.

In a thirteenth embodiment, the present disclosure provides an abrasivearticle according to any one of the tenth to twelfth embodiments,wherein the abrasive particles comprise shaped abrasive particles.

In a fourteenth embodiment, the present disclosure provides an abrasivearticle according to the thirteenth embodiment, wherein the shapedabrasive particles comprise precisely-shaped abrasive particles.

In a fifteenth embodiment, the present disclosure provides an abrasivearticle according to the thirteenth embodiment, wherein the shapedabrasive particles comprise precisely-shaped triangular platelets.

In a sixteenth embodiment, the present disclosure provides an abrasivearticle according to any one of the tenth to fifteenth embodiments,wherein the abrasive article is a coated abrasive article.

In a seventeenth embodiment, the present disclosure provides an abrasivearticle according to any one of the tenth to sixteenth embodiments,wherein the abrasive article is a nonwoven abrasive article.

In an eighteenth embodiment, the present disclosure provides an abrasivearticle according to any one of the tenth to seventeenth embodiments,wherein the substrate comprises a fiber scrim.

Objects and advantages of this disclosure are further illustrated by thefollowing non-limiting examples, but the particular materials andamounts thereof recited in these examples, as well as other conditionsand details, should not be construed to unduly limit this disclosure.

EXAMPLES

Unless otherwise noted, all parts, percentages, ratios, etc. in theExamples and the rest of the specification are by weight.

MATERIALS USED IN THE EXAMPLES ABBREVIATION DESCRIPTION AND SOURCE PFPhenol-formaldehyde resin (75% solids in water) having a phenol toformaldehyde molar ratio of 1:1.5-2.1, and catalyzed with 2.5 percent byweight potassium hydroxide. 835 An alkali-swellable acrylic polymeremulsion (ASE) obtained under the trade designation ACUSOL 835 from TheDow Chemical Company, Midland, Michigan, as an aqueous emulsion with28.75% solids content. 842 An alkali-swellable acrylic polymer emulsion(ASE) obtained under the trade designation ACUSOL 842 from The DowChemical Company as an aqueous emulsion with 18.02% solids content. 820A hydrophobically-modified alkali-swellable acrylic polymer emulsion(HASE) obtained under the trade designation ACUSOL 820 from The DowChemical Company as an aqueous emulsion with 29.77% solids content 880 Ahydrophobically-modified ethoxylated urethane (HEUR) polymer obtainedunder the trade designation ACUSOL 880 from The Dow Chemical Company asa 35.00% solids solution in 60% propylene glycol/40% water 1130 Analkali-swellable acrylic polymer emulsion (ASE) obtained under the tradedesignation RHEOVIS AS 1130 from BASF, Florham Park, New Jersey, as anaqueous emulsion with 31.3% solids content 1162 Ahydrophobically-modified alkali-swellable acrylic polymer emulsion(HASE) obtained as RHEOVIS HS 1162 from BASF as an aqueous emulsion with35.2% solids content. FIL1 Calcium carbonate, obtained from HuberEngineered Materials, Atlanta, Georgia, as HUBERCARB Q325 FIL2 Calciumsilicate obtained as 400 WOLLASTOCOAT 10014 from NYCO, Willsboro, NewYork FIL3 Hydrophilic amorphous fumed silica obtained as CAB-O-SIL M-5from Cabot Corporation, Alpharetta, Georgia FIL4 Cryolite obtained asCRYOLITE RTN-C from FREEBEE A'S, Ullerslev, Denmark. SAP1 Shapedabrasive particles were prepared according to the disclosure of U.S.Pat. No. 8,142,531 (Adefris et al). The shaped abrasive particles wereprepared by molding alumina sol gel in equilateral triangle-shapedpolypropylene mold cavities. After drying and firing, the resultingshaped abrasive particles, which were shaped as truncated triangularpyramids, were about 1.4 mm (side length) × 0.35 mm (thickness), with adraft angle approximately 98 degrees. RIO Red iron oxide pigmentobtained under the trade designation KROMA RO-3097 from Elementis, EastSaint Louis, Illinois

Test Methods Viscosity Measurement

The flow characteristics of the phenolic copolymer mixtures werecharacterized by continuous flow rheometry using a TA InstrumentsDiscovery Hybrid Rheometer 3 (TA Instruments, New Castle, Del.) equippedwith steel 40 mm parallel plate upper geometry, and a TA instrumentsAdvanced Peltier Plate (APP) as the lower geometry and temperaturecontrol. Samples approximately 2 milliliters in volume were loaded ontothe APP via pipet and the upper plate was brought to a gap height 1050micrometers. Excess sample was trimmed away, and the exposed edge of thesamples were coated with a thin layer of silicone oil (obtained fromAlfa Aesar, Tewksbury, Mass.; kinematic viscosity of 5.084×10⁻⁵ m²s⁻¹ at25° C.) to minimize water evaporation form the sample. The upper platewas then brought to a gap height of 1000 micrometers and held at thatdistance for the duration of the measurement. Individual samples wereallowed to thermally equilibrate in the instrument for 180 secondsbefore testing. The shear rate dependent flow behavior of the mixtureswas investigated at 25° C. using a logarithmic ramp over 180 secondsfrom 0.01-100 Hertz (Hz) selecting 10 individual rates per decade. Thepseudoplastic character (I) of each sample was characterized by theratio of the viscosity measured at 0.01 s⁻¹ to the viscosity measured at10 s⁻¹. Table 5 is a tabulation of the viscosity measured at 0.01 s⁻¹,10 s⁻¹ and 1 for all samples tested.

Particle Counting

Images of samples before and after curing were obtained using a MIGHTYSCOPE 5M digital microscope (Aven Tools, Ann Arbor, Mich.) with acircularly polarizing filter at a working distance of 8.5 cm. Imageresolution was 2592 pixels by 1944 pixels. Images were subsequentlyanalyzed using IMAGE-PRO PREMIER 64-bit software (Media Cybernetics,Inc., Rockville, Md.). Regions of the images corresponding to SAP1 weredigitally identified by analyzing the image using the red green blue(RGB) pixel analysis mode and thresholding on the blue channel between150 and 255 as well as the green channel between 145 and 250. Regionstouching the edge of the image were excluded from analysis as well asregions less than 0.1 square millimeters in area. The individual regionswere sorted according to calibrated area and aspect ratio intocategories four categories representing single particles standingupright, two particle clusters and particles lying flat, clusters ofthree or more particles, and shards of SAP1 according to the ranges inTable 1. The aspect ratio is defined as the ratio between the major axisand minor axis of an ellipse equivalent to the specific region.

TABLE 1 Category Area (mm²) Aspect Ratio Single 0.3-0.7 1.8-4.8 Doubleand Fallen 0.5-1.4 1.0-2.0 Cluster ≥1.4 ≥1.3 Shard 0.1-0.5 1.0-2.5

Examples 1-14 and Comparative Examples A-D

Examples and Comparative Examples were separately prepared by combiningall components into 4-ounce (120 mL) 70 mm diameter polypropylenestraight walled jars (Taral Plastics, Union City, Calif.) according toTables 2-4 and sealed with a screw cap. The jars were mixed in a DualAsymmetric Centrifuge (DAC) SPEEDMIXER (FlackTek Inc., Landrum, S.C.)for 2 minutes at 2750 rpm and then allowed to cool to ambienttemperature (approximately 23° C.). If the mixture was not used fortesting immediately it was stored in a refrigerator at 10° C. until use.

TABLE 2 COM- EXAMPLE PONENT 1 2 3 4 5 6 7 Amount in grams PF 16.55 16.5516.55 16.55 16.55 16.55 21.85 835 1.05 2.13 5.49 11.59 1.40 820 1.02 8800.87 FIL1 13.45 13.45 13.45 13.45 13.45 13.45 17.75 FIL3 0.40 % ResolePhenolic of total weight of Resole Phenolic + Organic polymeric rheologymodifier 97.6 95.3 88.7 78.8 97.6 97.6 97.6 % Organic polymeric rheologymodifier of total weight of Resole Phenolic + Organic polymeric rheologymodifier 2.4 4.7 11.3 21.2 2.4 2.4 2.4

TABLE 3 COM- EXAMPLE PONENT 8 9 10 11 12 13 14 Amount in grams PF 26.0426.04 26.04 26.04 26.04 27.2 18.68 835 3.46 8.58 1.24 820 3.35 880 2.841130 3.18 1162 2.83 FIL1 13.45 13.45 13.45 13.45 13.45 13.45 17.75 FIL30.40 % Resole Phenolic of total weight of Resole Phenolic + Organicpolymeric rheology modifier 95.2 95.1 95.2 95.2 95.1 88.0 97.5 % Organicpolymeric rheology modifier of total weight of Resole Phenolic + Organicpolymeric rheology modifier 4.8 4.9 4.8 4.8 4.9 12.0 2.5

TABLE 4 COMPARATIVE EXAMPLE A B C D COMPONENT Amount in grams PF 16.5521.58 26.04 20.84 FIL1 13.45 17.52 FIL2 22.74 18.20 FIL3 0.39 0.39 WATER0.60 0.78 1.21 0.97

Viscosity Measurements of Examples 1-14 and Comparative Examples A-D

Samples were tested according to the Viscosity Measurement Test Methodas described hereinbefore. Results are reported in Table 5, below.

TABLE 5 Viscosity (Pa · s), 25° C. EXAMPLE 0.01 s⁻¹ 10 s⁻¹ I 1 304.2945.45 6.70 2 2852.96 90.42 31.55 3 9368.78 141.86 66.04 4 13368.80183.12 73.01 5 288.16 64.39 4.47 6 41.06 18.74 2.19 7 1023.06 63.3516.15 8 588.52 63.38 9.29 9 826.25 132.71 6.23 10 49.05 31.42 1.56 11936.69 83.79 11.18 12 1006.86 236.92 4.25 13 8870.14 179.11 49.52 1461.64 34.58 1.78 COMPARATIVE 27.62 6.44 4.29 EXAMPLE A COMPARATIVE694.78 18.44 37.68 EXAMPLE B COMPARATIVE 14.49 9.53 1.52 EXAMPLE CCOMPARATIVE 790.84 28.42 27.82 EXAMPLE D

Examples 15-20 and Comparative Examples E-G

To evaluate the ability of the examples to retain the orientation ofabrasive particles in a coated abrasive construction, additionalexamples using the resin compositions coated onto a backing were made.RIO (0.5% based on total resin weight) was added to formulations ofexamples 1, 7, 8, 11, 12, and Comparative Examples A-C to increase theoptical contrast between the resin and SAP1. The samples were mixed in aDAC SPEEDMIXER (FlackTek Inc.) for 1 minute at 2750 rpm and then allowedto cool to ambient temperature (approximately 23° C.). If the mixturewas not used for coating immediately it was stored in a refrigerator at10° C. until use.

The resins were coated onto 8 inches×4 inches (20.32 cm×10.16 cm)sections of polyester backing (polyester backing described in Example 12of U.S. Pat. No. 6,843,815 (Thurber et al.) using a stainless steel rodand 3M CIRCUIT PLATING TAPE 851 as a spacer to maintain even coatingthickness. The coated samples were approximately 6 inches×3.5 inches(14.7 cm×8.6 cm) in size. Shaped abrasive particles (SAP1) weretransferred in a batch process as described in U.S. Pat. Appl. Publ. No.2016/0311084 A1 (Culler et al.). The shaped abrasive particles werearranged as shown in FIG. 2 of U.S. Pat. Appl. Publ. No. 2016/0311084 A1(Culler et al.). The areal density of SAP1 was measured to be maximally416 particles per square inch (64.5 particles per cm²).

After placement of the SAP1, optical images of randomly chosen regions(2.75 cm×2.10 cm) of the coated samples were obtained using a MIGHTYSCOPE 5M digital microscope (Aven Tools, Ann Arbor, Mich.) with acircularly polarizing filter at a working distance of 8.5 cm. Imageresolution was 2592 pixels by 1944 pixels.

The coated samples were then cured in a forced air oven set to 90° C.for 60 minutes. After curing, optical images of the three regions whichhad been previously imaged were obtained. Care was taken to ensure thatidentical regions of each sample were imaged so that SAP1 orientationcould be directly compared before and after curing.

Images of each example and comparative example were according to theparticle counting test method above. Results are reported in Table 6.From the data that is contained in Table 6, it can be seen that theformulation with the polymer rheology control additives offer advantagesin the orientation on abrasive particles both before and after the resinis cured. Example 20 demonstrates that above a critical level ofadditive the abrasive particles are locked in place as soon as they makecontact with the resin.

TABLE 6 DOUBLE & TOTAL SINGLE FALLEN NUMBER OF CURE SAP1, SAP1,CLUSTERS, SAP1 EXAMPLE RESIN STATE % % % COUNTED Comparative ComparativeUncured 68.6 27.0 3.7 2100 Example E Example A Cured 37.4 45.2 17.0 2099Comparative Comparative Uncured 77.4 19.5 2.6 2023 Example F Example BCured 60.0 33.7 5.2 2088 15 Example 1 Uncured 91.7 7.2 0.7 2088 Cured42.8 37.0 20.0 2050 16 Example 7 Uncured 48.7 34.1 17.0 1646 Cured 34.138.0 27.7 1593 Comparative Comparative Uncured 19.4 36.3 39.3 1241Example G Example C Cured 14.9 32.3 48.7 1256 17 Example 8 Uncured 48.732.2 7.7 1188 Cured 45.5 34.4 7.5 1170 18 Example 11 Uncured 81.5 15.62.3 1039 Cured 61.1 28.0 10.7 1042 19 Example 12 Uncured 62.0 30.1 7.51037 Cured 50.0 38.7 11.0 1034 20 Example 13 Uncured 73.7 23.9 0.95 419Cured 73.0 24.6 0.95 422

Examples 21-23

Coated abrasive Examples 21-23 were prepared using the make resin ofExample 8. The make resin was coated at 49° C. (120° F.) onto singedpolyester backing (polyester backing described in Example 12 of U.S.Pat. No. 6,843,815, Thurber et al.) using a 10.2-cm heated knife (49° C.or 120° F.) at a 0.2799 mm gap. The make weight was 163.7 g/m². SAP1 waselectrostatically coated onto the coated abrasive samples and mineralweights were varied (314 g/m², 418 g/m², 523 g/m²) as reported in Table7. The finished samples were approximately 48 inches×4 inches (121.9cm×10.2 cm) in size. The belt samples were then cured in a forced airoven for 90 minutes at 90° C. and 60 minutes at 103° C. The belt sampleswere then coated with a size coat composition, followed by a supersizecoat composition. The size coat composition was prepared by charging a3-liter (L) plastic container with 431.5 g of PF, 227.5 g of FIL2, 227.5g of FIL4 and 17 g of RIO, mechanically mixing and then diluting to atotal weight of 1 kilogram with water. The prepared size coatcomposition was then coated onto the examples at a coverage rate of 483g/m² with a 75-cm paint roller and resultant product was cured at 90° C.for 60 minutes and then at 102° C. for 8 hours more. The supersize coatcomposition was prepared according to Example 26 of U.S. Pat. No.5,441,549 (Helmin) starting at column 21, line 10. The preparedsupersize coat composition was then coated onto the examples using a75-cm paint roller with a coverage of 462 g/m². The product was cured at90° C. for 30 minutes, 8 hours at 102° C. and 60 minutes at 109° C.

Grinding Test

A grinding test was conducted on 10.16 cm by 91.44 cm belts convertedfrom the coated abrasives of Examples 21-23. The workpiece was a 304stainless steel bar on which the surface to be abraded measured 1.9 cmby 1.9 cm. A 20.3 cm diameter 70 durometer rubber, 1:1 land to grooveratio, serrated contact wheel was used. The belt was run at 2750 rpm.The workpiece was applied to the center part of the belt at a normalforce of 4.4-6.8 kg. The test consisted of measuring the weight loss ofthe workpiece after 16 seconds of grinding. The workpiece would then becooled and tested again. The test was concluded after 40 cycles. Theinitial cut in grams was defined at total cut after 2 cycles. The totalcut in grams was defined has total cut after 40 cycles. The test resultsare reported in Table 7. A commercially available 984F 36+I4 Cubitron IIbelt (3M Company) was also tested for comparison, and is labeled asComparative Example H.

TABLE 7 MINERAL INITIAL TOTAL WEIGHT, CUT, CUT, EXAMPLES g/m² gramsgrams 21 314 64.07 886.35 22 418 63.23 917.18 23 523 47.13 580.19Comparative — 50.30 578.31 Example H

All cited references, patents, and patent applications in thisapplication that are incorporated by reference, are incorporated in aconsistent manner. In the event of inconsistencies or contradictionsbetween portions of the incorporated references and this application,the information in this application shall control. The precedingdescription, given in order to enable one of ordinary skill in the artto practice the claimed disclosure, is not to be construed as limitingthe scope of the disclosure, which is defined by the claims and allequivalents thereto.

1. A method of making an abrasive article comprising: disposing acurable composition on a substrate, wherein the curable compositioncomprises a resole phenolic resin and an organic polymeric rheologymodifier selected from hydrophobically-modified ethoxylated urethanepolymers, wherein the organic polymeric rheology modifier comprises analkali-swellable/soluble polymer, and, on a solids basis, wherein theamount of the resole phenolic resin comprises from 75 to 99.99 weightpercent of the combined weight of the resole phenolic resin and theorganic polymeric rheology modifier; adhering abrasive particles to thecurable composition; and at least partially curing the curablecomposition.
 2. (canceled)
 3. The method of claim 1, wherein, on asolids basis, the amount of the resole phenolic resin comprises from 85to 99.99 weight percent of the combined weight of the resole phenolicresin and the organic polymeric rheology modifier.
 4. The method ofclaim 1, wherein the abrasive particles comprise shaped abrasiveparticles.
 5. The method of claim 4, wherein the shaped abrasiveparticles comprise precisely-shaped abrasive particles.
 6. The method ofclaim 4, wherein the shaped abrasive particles comprise precisely-shapedtriangular platelets.
 7. The method of claim 1, wherein the substratecomprises a backing member having first and second opposed majorsurfaces, the method further comprising: disposing a size layerprecursor onto at least a portion of the abrasive particles and said atleast partially cured curable composition; and at least partially curingthe size layer precursor to provide a coated abrasive article.
 8. Themethod of claim 1, wherein the substrate comprises a lofty open nonwovenfiber web.
 9. The method of claim 1, wherein the substrate comprises afiber scrim.
 10. An abrasive article comprising abrasive particlesadhered to a substrate by a binder material comprising an at leastpartially cured resole phenolic resin and an organic polymeric rheologymodifier selected from hydrophobically-modified ethoxylated urethanepolymers, wherein the organic polymeric rheology modifier comprises analkali-swellable/soluble polymer, wherein the amount of the at leastpartially cured resole phenolic resin comprises from 75 to 99.99 weightpercent of the combined weight of the at least partially cured resolephenolic resin and the organic polymeric rheology modifier. 11.(canceled)
 12. The abrasive article of claim 10, wherein the amount ofthe at least partially cured resole phenolic resin comprises from 85 to99.99 weight percent of the combined weight of the at least partiallycured resole phenolic resin and the organic polymeric rheology modifier.13. The abrasive article of claim 10, wherein the abrasive particlescomprise shaped abrasive particles.
 14. The abrasive article of claim13, wherein the shaped abrasive particles comprise precisely-shapedabrasive particles.
 15. The abrasive article of claim 13, wherein theshaped abrasive particles comprise precisely-shaped triangularplatelets.
 16. The abrasive article of claim 10, wherein the abrasivearticle is a coated abrasive article.
 17. The abrasive article of claim10, wherein the abrasive article is a nonwoven abrasive article.
 18. Theabrasive article of claim 10, wherein the substrate comprises a fiberscrim.